The UK government scheme allowing EU citizens to remain post-Brexit is in danger of being upended, legal experts have warned, after a series of conflicting court rulings over social welfare payments to French and Slovenian citizens and the relative of a Spanish woman living in Britain.

In May, one county court judge found against Islington council, which had rescinded a Slovenian software engineer’s right to emergency housing after he lost work during the pandemic.

But in another case, in February, brought against Oldham council on behalf of a woman whose Spanish daughter was living in the UK, the judge found the opposite.

Then on 8 July, in a third ruling, the high court judge Justice Robert Jay dismissed a case taken on behalf of a French citizen who had deteriorating health and was seeking housing assistance.

The French woman, who suffers from a rare genetic condition that affects connective tissue, moved to the UK in November 2020 to live with her mother, the grandmother of her two children, one of whom has autism and the same genetic disorder.

Soon after arriving, she got a job as a teaching assistant but couldn’t take up the job because “she couldn’t provide the necessary references”, according to high court documents. She was also granted pre-settled status by the Home Office, long before the deadline of June the following year.

In December 2023, the French woman’s health had deteriorated. She was sectioned under the mental health act and, in January 2024, was discharged from secure psychiatric care.

In March, she was placed in “step down” accommodation: supported accommodation for those discharged from hospital but not ready to live independently. At this point a further application for housing was made, which was again rejected by the council.

Jay found in the council’s favour, which essentially argued the Brexit withdrawal agreement did not confer rights on pre-settled citizens other than visa-free immigration status.

He rejected the argument that pre-settled status (PSS) “accords immediate and unfettered access to all the rights”. PSS, he said, was only “unconditional for the purposes of UK immigration law”.

And he was blunt about those who had framed the citizens rights clauses in the EU-UK withdrawal agreement. “In my judgment, the framers of article 18(1) have created an entity whose fundamental characteristics, like the quantum particle, does not allow itself easily to be pinned down,” Jay said.

The University of York law professor Charlotte O’Brien said the three rulings would have terrible real life consequences, akin to Windrush for vulnerable EU citizens.

“It could mean that years and decades from now, people with settled status under the EUSS [EU settlement scheme] may find they have no proof that they ever had withdrawal agreement-based rights.”

She recalled a parliamentary exchange in which Sajid Javid, the then home secretary, was asked why the EUSS was compulsory. He answered: “In a word, Windrush.”

“The whole idea was to avoid a situation where we didn’t know who had documentary evidence of this international right to reside. That now has been changed by the court rulings,” she said.

Catherine Barnard, a professor of EU law at Cambridge University, warned the rulings had caused “confusion for frontline services” and could “lead to further inconsistencies in the application of benefit rules”.

Without government intervention it could take years for a definitive ruling on the matter by the supreme court, but the home secretary could fix it at a “stroke of a pen” through a statutory instrument, said O’Brien.

“The government could prevent the disaster of Windrush II by simply declaring that EU citizens and their family members with EUSS status come within the scope of the withdrawal agreement. This would not be controversial; to most people it would seem like stating the obvious. It was, after all, the whole purpose and rationale of the EUSS.”

A spokesperson for the Home Office hinted that a review was possible. They said: “EU citizens with pre-settled status can access benefits and services on the same basis as applied under free movement rules, as agreed by the last government.

“The EU settlement scheme has provided millions of EU citizens and their eligible family members with the immigration status they need to continue living and working in the UK and we remain committed to this work while the new home secretary decides on the future of departmental policies.”